Blind stitch sewing machine



June 1, 1954 c, w, MUELLER 2,679,814

BLlND STITCH SEWING MACHINE 6 Sheets-Sheet l Filed Dec. 27, 1948 w 3 J 14 Q 5 3 I JNVENTOR.

A TTOENEY n 1, 1954 c. w. MUELLER BLIND STITCH SEWING MACHINE 6 Sheets-Sheet 2 Filed Dec. 27, 1948 ATTOQN Y J 1, 1954 c. w. MUELLER BLIND STITCH SEWING MACHINE 6 Sheets-Sheet 4 Filed Dec. 27, 1948 INVENTOR. M 7

14 TTOQNEY June 1954 c. w. MUELLER BLIND STITCH SEWING MACHINE 6 Sheets-Sheet 5 Filed Dec. 27, 1948 INVENTOR.

4 7- rop/vsy June 1, 1954 c w, MUELLER 2,679,814

BLIND STITCH SEWING MACHINE I Filed Dec. 27, 1948 6 Sheets-Sheet 6 INVENTOR.

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,4 TTOENEY Patented June 1, 1954 BLIND STITCH SEWING MACHINE Charles W. Mueller, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, a

corporation of Maine Application l) ecember 27, 1948 Serial No. (57,268

4 Claims.

1 The invention herein disclosed-relates to sewing machines. More particularly, the invention relates to sewing machines in which the work is presented to the stitch-forming mechanism in the form of a node, such for example as is the case in the so-called blind-stitch sewing machine.

Objects of the invention are to provide a machine of the kind mentioned that is comparatively simple in construction; to provide a machine of this kind that is, by a simple manual control, convertible from a two to one or skip-stitch operation to a one to one operation; and to provide such amachine that requires a minimum of effort for lowering the work support for the insertion and'removal of'work.

The foregoing objects, and certain advantages that will hereinafter appear, are realized in the embodiment of the invention illustrated, as an example, in the accompanying drawings and described in detail below.

The drawings include:

Fig. l which is a plan view of a blind-stitch sewing machine embodying the invention;

Fig. 2 which is a front elevation of the same;

Fig. 3 which is a fragmentary sectional view of the same taken on the line 3-3 of Fig. 2;

Fig. 4 which is a fragmentary, vertical, sectional view of the same, taken on the irregular line 4-4 of Fig. 3;

Fig. 5 which is a sectional plan, taken on the line 5-5 of Fig. 3;

Figs. 6, 7, S and 9 which are transverse sectional views taken on the irregular lines 66, '|l, 88 and 99 of Fig. 4;

Fig. 10 which is a partial, sectional view taken on the line iiilil of Fig. 5;

Fig. 11 which is a partial, sectional view similar to Fig. 10, but showing the parts in a different position;

Fig. 12 which is a bottom plan taken on the line 12-42 of Fig. 10;

Fig. 13 which is a partial, sectional view taken on the line l3i3 of Fig. 5; and

Figs. 14, 15 and 16 which show in elevation certain parts of the machine in different positions of their movement.

In general, a machine such as that disclosed in this application includes a presser foot that has an opening therethrough, through which opening nodes of the material being sewn are projected.

Stitch-forming mechanism is arranged on one side of the presser foot. In a chain-stitch machine such as that illustrated, the stitch-forming mechanism includes a curved needle and a -loopeig -in the lock-stitch machine, a hook carrying mechanism ing a bobbin cooperates with the needle for forming the stitches. Work-presenting mechanism is arranged on the side of the presser foot opposite to that side adjacent to which the stitchformingmechanism is arranged. Fundamentally, the work-presenting'mechanism consists of a node-former which periodically, and in timedrelation with respect to the operation of the stitch-forming mechanism, presents a node of the material being sewn through the opening in the presser foot and in a position such that it is in the path of the needle. Operating mechanism is provided for operating both the stitchforming mechanism and the node-forming mechanism in proper timed relation. It is primarily with this operating mechanism that the invention herein disclosed relates.

All of the operating mechanism, in the machine illustrated in the drawing, is mounted in a frame or housing. This frame comprises a base I, a post or standard 2 extending from the base at the rear thereof, an arm 3 extending from the upper end of the post, a'forwardly extending arm 6, secured to the end of the arm 3, and a work table 5 secured to the base at the front thereof and extending to the forward end of the arm 4, that is, the end near the operator. The several sections of the frame are hollow and various parts of the operating mechanism for the stitchforming mechanism and the node-forming mechanism are mounted within these hollow sections.

A main shaft 6 is journaled in the post 2 and the arm 3. The shaft extends through the post 2 and has mounted on the extended end thereof a combined pulley 1 and hand-wheel 8. The pulley l is driven through a belt 9 from an electric motor (not shown) to which it is directly connected, or from a power shaft (not shown). The arm 4 carries a presser foot 10 which is fixed on the end of the arm and which overhangs the end of the work table 5. This presser foot is of the usual and wellknown construction. It has an opening I I therethrough, through which opening, during the operation of the machine, nodes of the material operated upon extend.

v, The particular machine illustrated in the drawing is a chain-stitch,v blind-stitch machine. The stitch-forming mechanismof this machine is of the usual andwell known kind that is used in sewing machines of this type. This stitch-formincludes a needle-bar shaft l2 "that is journaled in the arm i and extends through the forward end of the arm. On the extended end of the shaft 12, there is mounted a needle-bar .13 which carries a curved needle l4. Through The work operated upon, in the-region of the:-

stitch line, is supported against the under side of the presser foot by a-work support which consists of a pair of work-supporting platens l6 and [1. These platens are mounted for independent pivotal movement and for'movement towards and away from the presser foot. They are resiliently urged towards the presser foot. Both are mounted in the same manner. The mounting for the platen I! includes a: lever H3; in the nature of abell-crank" lever; that is pivotally mounted on a shaft 1 9. Onexarm: l8a of the lever is curved, as shown, and on the end thereof, there: is formed a boss l8b. A pivot pin is mounted in the boss and extends there.- from. A bracket l'l'a formed'on the platen- I1 is pivotally.- mounted onthepivotpin 20; Another arm l8c of the lever I8'has secured thereto one end of a spring 21. The'other end ofthe spring 2! is secured to an' adjustable anchor pin ZZthreaded through an openingf in the side wall of the work table 5: A check nut 23- secures the anchor pin in adjusted position. The spring 2| is a comparatively light spring as the function of the platens-is merely-to support the portion of the work operated upon against the presser foot.

The end portion of the work: table extending under the presser footis of much greater distance from the presser foot than thework table of the common machine of this kind; The distance between the work table and presser foot is sufiicient, when unobstructed, to permit the ready insertion and removal of work between the presser foot and the work table. For the purpose of readily permitting insertion and removal of work; the platens areretractable; the work table is fixed. To this end, the lever l8 of the platen I1. is provided with a lug l8d. A like lug is formed on thecorresponding lever for the platen 16 which is-indicated-by the numeral l6. Underlying these lugs, andnormally spaced from them, there is a rod .24 whichextends from a-bushing or collar 25that-is securedto a shaft 26. The rod isnormally spaced: from the lugs to permit limited independentmovement ofthe platens. Upon rotating the shaft 26, the platen supporting levers, such as thelever. I8, are moved to withdraw the platens toaposition away from the presser foot. Rotation of'the shaft 26 to withdraw the platens is effected, manually, through a knee press 21.

The knee press Z'l'is secured to an offset portion' 28a of a rod'28' whichis' secured, .through a connector 29, to a rod-30'. This rod, 30 extends into the base I and it is journal'ed' therein. Within the base I, there is secured to the rod 301 a lever 31. Adjacent theend of this lever, there is pivotally secured'one end offa link 32. the other end-of which is pivotally secured to the end of a lever 33" that is secured on the shaft26. When the knee press 21 (Figs. 1 and 2) is moved to the right, the rod 311 is rotated counterclockwise. The lever 3'! draws the link down and'rotates the shaft 26"t'o withdraw the platens to their open position, away from the presser foot.

The work-presenting mechanism for presenting work to the needle includes an oscillating node-former 34 of the sector-disc type, having two steps or sections of different radius 34a and 34b. The node-former is mounted on the endiofia-shafti35 that. is'rjournaled'in spaced bearings 36- and-31 of a'- cradle 3-81 The cradle 38 is pivotally mounted on centering pins 39 and 40 threaded through brackets 4| and 42 extendinginwardly from the side wall of the Work table. The cradle 38, and in consequence the node-former 3'4 isaresiliently held in adjusted,

- operativeposition by a heavy spring 43. One end ofthisspringis secured to a lug 44 extending from the cradle; and the other end is secured to an adjustable anchor pin 45 threaded through an opening in the front wall of the work table. The force exerted on the cradle by the spring 43 may bead'justedlto a limitedextent, by adjustingtheanchor-pin 45. The anchor pin 45 is held inadjusted-position by a checknut-46.

The node-former isoscillated in timed relation with respectzto; the stitch-forming and. feed mechanism. In the-upper position, adjacentthe presser foot, the node-former forcesa'node: of the-material operated-upon through the opening in the presser footand into the-path of the needle; After thepassage of. theneedle, the node-former is withdrawn to a-position away from-the presser foot. This'iseflected through oscill'ationof the'shaft 35. When additional materiaLsuohfor exampleas seams; passes under the presser foot, the:nodeformer must yield. It

is; thus,qyieldingly mounted as above described.

The position of the node-former, in node'- forming position", with respect to the presser-foot, determinesthe extent or.- height of the node formed, for the particular material, and in consequence, the depth of penetration of the needle. In the: machine illustrated, the depth of penetration-of: theneedle is adjustable through adjustment of: the-f cradle 38-, that is,,by limiting themovement of thecradle under the action of thespring. 43. Forthisrpurpose, there isprovidedi'azradjustingscrew arrangement, designated-generally by thenumeralfl, in. which an adjusting screw acts directly on the cradleto limit the upward movement of the cradle under the action of the spring 43.

Theshaft 35, on which the node-former is mounted,.is-o scillated througha chain of actuating mechanism thatis driven from the main shaft 6. In:the machine illustrated inthe drawings, the shaft 35 is-differentially oscillated. In thismanner, the. node-former moves to different, rotative positions, with respect to the path of the needle, on successive oscillations. For the purpose of sdactuating the node-former; a compound eccentric is utilized. This eccentric is mounted: on the main shaft 6 of the machine and it includes an eccentric 48 that. is. secured directlyto the main shaft through-set screws 49. Surroundingthe eccentric 48, there is another eccentric 50. The exterior surfacev orperiphery of the eccentric 5ll is-.-inthe form of asector' of a sphere. An eccentric; strap 5 I', having an inner surface complementary to the spherical-sector surface of the eccentric 50, surrounds the eccentric 50. The eccentric-50 is secured to a plate 52'for rotation therewith. The plate 52.

is free ontheshaft'and' hasa hub 53' formed thereon. Mounted'on the hub 53; and secured to' the" plate for-rotation" therewith; there isa spur gear 54. The gear 54 meshes with a gear carries a gear 5'! which is secured to the hub and the gear 55 for rotation therewith. The gear 51 meshes with a gear 58 that is secured to the main shaft by set screws 59. The arrangement is, in effect an arrangement of back gears for driving the eccentric 50. The ratio of these gears is such, that the eccentric 50 is driven at onehalf of the speed of the main shaft. Thus, when the eccentric 48 is in a down position, in which position it has moved the node-former to its most forward position towards the path of the needle, the eccentric 50 will on one stroke be adding to the stroke of the eccentric 48 and on the next stroke will be subtracting from the stroke of the eccentric 48. Thus, a different movement of the eccentric strap 5| is obtained on successive movements thereof for each rotation of the main shaft.

A curved, tubular connecting rod 80 is connected at one end to the eccentric strap 5 I. This connecting rod is curved and extends from the eccentric strap into the forward end of the base of the machine, and the other end thereof is connected, through a ball and socket joint 8 I, to one end of a rocker arm 62. On the lower or under side of the connecting rod 60 there is secured a lateral vane 63. While the connecting rod is connected at both ends through ball joints, and may insofar as these joints or connections are concerned, oscillate or vibrate sideways, the vane 63 keeps the connecting rod from swinging or vibrating when the machine is operating. Both the extension 64 on the eccentric strap, to which the connecting rod is secured, and the ball socket fixture 65, at the opposite end of the connecting rod, are hollow. In this way, oil introduced in the oil cup 5'6 on the upper side of the eccentric strap 5| passes around the eccentric and through the connecting rod to the ball joint on the rocker arm 62. It is to be noted that the connecting rod directly connects the eccentric 5i and the rocker arm 62 within the forward end of the base of the machine. By use of this connecting rod, the jack-shafts and bell crank levers that have formerly been used in order to transmit oscillating motion from the main shaft to the base of the machine have been eliminated. In addition, the direct connection made by this connecting rod and the lightness in weight of the hollow connecting rod permit greater speed in operation of the machine.

The rocker arm 52 consists of a hub 51 and two, oppositely extending, integral arms 68 and 69, the latter being connected to the connecting rod fill. The arms 68 and 69 are spaced axially of the hub. The hub 51 is journaled on an eccentric bushing "It, which eccentric bushing is fixed to a shaft II that is journaled in bearing arms I2 and E3 of a supporting bracket secured in the base of the machine. The end of the shaft II extends through the bearing arm I3. and has a sector disc M mounted thereon and fixed thereto. The sector disc M has a substantially radial edge Ma and a substantially tangential edge 14b. Intermediate the ends of the shaft II and between the rocker arm 62 and the bearing bracket I2, a gear I5 is fixed to the shaft 'II for rotation therewith. The gear I5 meshes with a gear 16 that is fixed on the end of a shaft TI, which extends through a depending bearing arm I8, and is journaled therein. On the end of the shaft 11, opposite to that end to which the gear I6 is secured, a lug I9 is fixed on the shaft. The lug 19 serves as a collar to retain the shaft in the bearing and also as a crank arm to which one end of a spring as is secured. The other end of the spring is secured to a pin fixed in the side wall of the base; a link 8| is interposed between the spring and the lug I9, the link being pivotally secured to the lug. The spring 80, acting through the shaft TI and gears I6 and 15, tends to rotate the shaft II on which the eccentrio bushing I0 is mounted. Rotation of the shaft I I, under the action of the spring, is limited by a manually movable stop 82 acting against the edge 14a of the disc I4.

- The movable stop 82 (Figs. 10 and 12) is an eccentric cam, bevelled on its eccentric end 82a for the purpose of securing, in all positions, full engagement with the edge 1 3a of the disc 14. The movable stop 82 is fixed to the lower end of a vertical shaft 83. On the upper surface of the work table, and received in a depression formed therein, there is a disc 84 secured to the shaft 33. A finger piece 84a is provided on the disc 84 so that the operator may move the shaft and the stop 82- between two different positions. For each position, there is a depression, 84b and 840, on the under surface of the disc. A spring pressed, ball detent 85 cooperates with these depressions for retaining the stop in the position to which it is moved by the operator. In this way, the position of the eccentric I0 secured on the shaft Il may be changed by the operator. By thus changing the position of the shaft II, the machine may be converted from a skipstitch, or two to one machine, to a one to one machine and vice-versa, in a manner that will be hereinafter more fully described.

The arm 68 on the rocker arm 62 is connected through a link 86 to the arm of a crank 81 that is mounted on the end of the node-former shaft 35. The link 86 is connected both to the arm 58 and the crank 81 by ball and socket joints.

With the foregoing arrangement, it will be seen that the rocker arm is oscillated by the compound eccentric. This in turn, through the link 86,

- oscillates the node-former shaft 35 and in consequence the node-former 34. Because of the differential arrangement of the eccentric on the main shaft, the node-former shaft 35 is oscillated a different amount on successive oscillations.

With the stop 82 in the position shown (Fig. 10), the machine is set for skip-stitch operation, i. e. the depth of penetration will vary on successive oscillations. On the shorter oscillation, the node-former disc 34 will move (Fig. 14) from the rearward position indicated by the dotted outline 89 to the position indicated in full lines in which the low point 341) of the node-former is under the needle. On the next or longer stroke, the node-former will move to the position indicated by the dotted line designated by the numeral 90. In this position, the higher portion 34a of the node-former comes under the needle and the needle penetrates the material being sewn to a greater depth.

If the stop 82 is now rotated through the finger piece 84a, to the opposite position (Fig. 5), the shaft II will move under the action of the spring 80, and the disc will be oscillated as indicated in Fig. 15, that is to bring the higher portion or edge 34a beneath the needle on every oscillation. On one oscillation, the node-former moves from the position indicated at 9| to the position indicated at 92. On the next or shorter oscillation,

the node-former moves from the position shown at 9| to the position indicated in full. lines and designated by the numeral 93. Thus, inboth instances, the node-former moves so that: the higher edge 34a thereof comes up to the path of the needle and the needle penetrates the material' being sewn the same amount on every oscillation of the node-former. Thus, by manipulating the finger piece 84, the machine is readily converted from a skip-stitch machine or a socalled two to one machine, that is, a machinein which the depth of penetration of the needle varies on successive strokes, to a one to onemachine, that is a machine in whichthe depth of penetration is uniform on all strokes. The skipstitch machine is especially useful in hemming dresses. And, it is widely used for this purpose.

The link 86, connecting the rocker-lever arm 68 and the crank arm 8'! on the node-former shaft 35 permits the shaft 35 to move substantially vertically when it is necessary for thenodeformer to yield. In other words, this link 86 permits movement of the cradle 38, in which the shaft 35 is journaled, against the action of the spring 43, when the node-former passes over a thicker amount of material, such as when a seam passes through the machine.

From Figs. 8 and 9, it will be apparent that even with the work-supporting platens withdrawn, the node-former 34 may, depending upon its position, obstruct the insertion and removal of work between the presser foot and the platens. For this reason, in the machine illustrated, the node-former 34 is retracted when the knee press 27 is actuated, to the full extent; to a position (Figs. 7 and 16) in which there is a clear opening for the insertion and removal of work.

Manual retraction or withdrawal of the nodeformer is efiected by rotating the shaft H, through the gear 16, and so shifting the eccentric 70. On the gear 16, and extending from the side thereof, there is a stud 94 which constitutes a crank. This stud 94 is positioned to be engaged by a shoe 95 secured on the link 32.

The normal position of the shoe 95 is slightly above the horizontal plane passing through the axis of the shaft 11. It is held in this position by a spring 96. On the inner end of the rod 39, there is secured a collar 91 which carries a radial pin 97. One end of the spring 96 is secured to this pin and the other end of the spring is secured to a stationarypin 98, extending inwardly from the end wall of the base I.

The normal position of the shoe 95 is out of contact with andspaced above the stud 94. This relation permits a slight withdrawal of the work-supporting platens l6 and I! before the shoe engages the stud 94. The reason for this is to permit the operator to release the work while the machine is operating. The usual engagement of the platens and presser foot with the work does not permit the work to be turned in the machines. Heretofore, in machines of this kind, when it was necessary to turn the work, the operator had to stop the machine, open it, and then turn the work. By releasing the pressure on the platens, as above described, the work rides on the node-former and may be turned on the node-former as a pivot while the machine is operating.

When the machine is stopped, and the operator presses the knee press 21 the full extent, the shoe 95 engages the stud 94 androta-tes the gear 76. The gear 15 and shaft H are thus rotated in a two to one ratio, and the shaft H is rotated until the edge 14b (Fig. 11) engages the face ofv the cam. 82. The eccentric 10 is thus shifted. In Fig. 15, the eccentric 10 and the node-former 34 are shown in their normal position. When the machine is stopped, the lower end of the lever 69 is held by the connecting rod 69. Shifting of the eccentric 10 thus causes movement of the lever about its pivotal connection with the connecting rod 60 and retracts the node-former 34 to the position illustrated in Figs. 7 and 16. Upon release of the knee press, the'work-supporting platens and the nodeformer return to their normal positions. This is effected through the springs acting on the platens and the spring 96.

From the foregoing description of the embodiment of the invention illustrated in the drawing, it will be apparent to those skilled in the art that by this invention there is provided a machine of comparatively simple construction; a machine that is capable of high speed operation; a machine that is readily converted from a two to one, to a one to one machine; and a machine that requires a minimum of effort on the part of the operator for opening the machine for the insertion or removal of work.

It will be obvious that various changes may be made by those skilled in the art in the details of the embodiment of the invention illustrated in the drawings and described above within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. In a blind-stitch sewing machine, the combination comprising a presser foot having an opening therethrough, stitch-forming mechanism, a work support movable towards and away from the presser foot, work-presenting mechanism for presenting work to the stitch-forming mechanism including a movable node-former, movable toward and away from the presser foot, node-former moving mechanism for aifecting movement of the node-former in timed relation with the stitch-forming mechanism and to different positions with respect to the presser foot on successive movements thereof towards the presser foot including an eccentrically mounted rocker arm, manually operative means for moving the eccentric to shift the stroke of the node-former, and additional manually operative means for shifting said eccentric to move the node-former away from the presser foot for the removal or insertion of work.

2. In a blind-stitch sewing machine, the combination comprising a presser foot having an opening therethrough, stitch-forming mechanism, a work support movable towards and away from the presser foot, work-presenting mechanism for presenting work to the stitchforming mechanism including a movable nodeformer movable toward and away from the presser foot, node-former moving mechanism for affecting movement of the node-former in timed relation with the stitch-forming mechanism and to different positions with respect to the presser foot on successive movements thereof towards the presser foot including an eccentrically mounted rocker arm, manually operative means for moving the eccentric to shift the stroke of the node-former, and manually operative means for moving the work support away from the presser foot and means actuated thereby for moving said eccentric to move the node-former away from. the presser foot for the removal and in- .sertion of work.

3'. Ina blind-stitch sewing machine, the combination comprising a presser foot having an opening therethrough, stitch-forming mechanism operatively related to the presser foot, a work support movable toward and away from the presser foot, work presenting mechanism for presenting work to the stitch-forming mechanism including a node-forming oscillatable disc having a step therein, node-former moving mechanism for afiecting movement of the nodeforming disc in timed relation with the stitchforming mechanism and to different positions with respect to the presser foot on successive movements thereof toward the presser foot including a difierentially actuated eccentric and an eccentrically mounted rocker arm, and manually operative means for moving the rocker arm eccentric to shift the stroke of the nodeforming disc.

4. In a blind-stitch sewing machine, the combination comprising a presser foot having an opening therethrough, stitch-forming mechanism operatively related to the presser foot, a work support movable toward and away from the presser foot, work presenting mechanism for presenting work to the stitch-forming mechanism including an oscillatable, node-former disc having a step therein, node-former moving mechanism for afiecting movement of the nodeformer in timed relation with the stitch-form ing mechanism and to different positionswith respect to the presser foot on successive movements thereof toward the presser foot including a differentially actuated eccentric and an eccentrically mounted rocker arm, manually operative means for moving the rocker arm eccentric to shift the stroke of the node-former, means for moving the work support away from the presser foot, and means actuated simultaneously therewith for moving the rocker arm eccentric to move the node-former away from the presser foot for the removal and insertion of work. 

